I don't consider the 3 spot gourami to be in the peaceful catagory, and the pearl and snakeskin are.
For peacefull planted you could also consider the rainbow cichlid (herotilapia multispinossa), uaru but they get a bit larger.
For tank decorating inspiration try looking at the images returned when you google iwagumi. Or check out some of the contest entries on
http://showcase.aquatic-gardeners.org/ . The current work is so fantastic as to be hardly applicable to a community aquarium like you want, but I think you could find some ideas if you looked at the earlier years of the contest entries.
I have kept a group of snakeskins Before, I found them very shy and skittish until settled in. they displayed some really nice subtle yellow colors too, a nice alternative to common gourami species. the females I had grew quite large and fast. I would probably lean more towards The pearl gourami because at least they are easier to get hold of.
Rainbow cichlids are a great if I can find colorful ones locally, I once had a brown one I was convinced would turn out beautiful under the right conditions, it never showed a single drop of color for years, kinda dissapointing.
I did try a group of moonlight gourami once, they were very mean to eachother and weren't as hardy as other gourami, not one of my recommendations lol.
I would love an aquascape that utilizes Christmas Moss. I have ever multiplying amounts of it and I could probably pull of something interesting with it, I only started doing plants about a year ago, and I'm not into the whole Co2 high intensity planted tanks.
How many Scissor tail rasbora would be okay in a 120? I hear they can get quite large but I`ve only ever seen the 1" juveniles for sale. I would love to have a group of these, kind of like a more appropriate replacement for bala sharks. I would be tempted to go asian themed and make a biotope but I really want some corydoras and I`m not really that interested in having loaches.